To make worse; to diminish in quantity, value or excellence. An estate is impaired by extravagance or neglect. The profligate impairs his estate and his reputation. Imprudence impairs a man’s usefulness.

To weaken; to enfeeble. The constitution is impaired by intemperance, by infirmity and by age. The force of evidence may be impaired by the suspicion of interest in the witness.

To be lessened or worn out.

In crystallography, when a different number of faces is presented by the prism, and by each summit; but the three numbers follow no law of progression.

Diminution; decrease; injury.